Pressure relief valve



y 6, 1939. A. L PARKER 2,158,478

PRESSURE RELI EF VALVE Filed June 19; 1936 2 Sheets-Sheet 1 lllllill J a? llll 1 565 1 1 [a I i .|l||||" W hi; .QJ g 11 I I 1 I. m

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May 16, 1939. A. L. PARKER PRESSURE RELIEF VALVE Filed June 19. 1936 2 Sheets-Sheet 2 Patented May 16, 1939 UNITED STAT-ESPATENT OFFICE PRESSURE RELIEF VALVE Arthur L. Parker, Cleveland, Ohio Application June 19,

This invention relates to pressure relief valves which are adapted to be'used in fluid supply systems to regulate the pressure at which the fluid is delivered therefrom.

pressure and remain in such a position while the pressure of the issuing fluid is uniformly maintained at the point desired.

A further object of the invention is to provide,

in connection with a pressure relief valve, 9. pilot valve which opens under a predetermined pressure and, in so doing, causes the pressure relief valve to open.

A still further object is to provide improved means to hold the pressure relief valve steady, so

that it will not chatter.

The preferred embodiment of the invention and the manner in which it operates will be described in detail in connection with the accompanying drawings,

in which,-

Figure 1 is a side elevation of a valve embodying the invention.

Figure 2 is a section taken substantially on the line 2-2 of Figure 1.

Figure 3 is a plan view,

on an enlarged scale,

of the means for selectively setting the valve for a predetermined pressure and indicating the same.

Figure 4 is an enlarged the line 4- 4 of Figure 3.

Figures 5, 6 and '7 ar sectional view taken on e detail views showing successive positions of the parts in setting the valve.

As shown in the drawings, the housing II is provided with an inlet ll adapted to be connected with a supply chamber from which it receives fluid under pressure and is formed with a valve seat removable to permit the i0. Aspring IS with an outlet l2 which IS. .The outlet I2 is pressure reliei valve l4 within the housing housing urges the valve against the seat II.

The lower portion of the housing III is formed with an annular pressure chamber 11 about the reduced lower portion l 8 of the valve i4 adjacent 'the inlet H and the upper portion of the valve is reduced, as at It, ,leaving an annular chamber 20 which is in constant communication through a duct A relief port a chamber 23, in which rocably mounted. The v 2| with the chamber I1.

22 leads from the chamber 20 to a pilot valve 24 is recipalve 24 is adapted to be 1m, Serial No. sam a closed against its seat 25 by a spring 2&until it is opened by a predetermined pressure from the. chamber 20.

When the valves l4 and 24 are both closed, the pressures in the chambers I1 and 20 will be equal. The diameter of the valve seat It is slightly greater than the diameter 01' the reduced portion is of the pressure relief valve. Assuming that the major diameter of the valve I4 is a, that the diameter of the reduced portion [9 is b, and 10 that the diameter of the valve seat I3 is c; then the pressure tending to seat the valve is proportional to (t -b and the pressure tending to lift the valve is proportional to a=c=. Since o is greater than D, the valve will remain closed.

However, when the pressure reaches the predetermined point where the valve 24 opens, the fluid in the chamber escapes through the port 22 faster than it is built up through the duct 2 I, with the result that the valve l4 will open. Fluid will 20 then flow through the outlet l2 at the accumulated pressure in the chamber I! which was necessary to open the valve 24.

Another spring 21, preferably housed within the spring I! and shorter than the latter, comes 25 into action after the valve l4 has been raised slightly from its seat. This prevents the valve irom opening wider, maintaining the opening substantially constant for the peredetermined pressure, and prevents the valve from fluttering or chattering.

In case the pressure at the inlet I l' and in the chamber ll tends to rise above the predetermined pressure, a slight further rise of the pilot valve 24 relieves the potential excess pressure through the by-pass 2U, 29.

The pilot valve 24 is mounted within an extension 20 of the housing It, in which a follower II is slidably keyed, as at 22, and constitutes an adjustable seat tor the upper end 01 the spring.

26. An adjusting screw 33 is rotatably mounted in a plug 24 which closes the upper end of the housing extension 20.

Longitudinal movement of the screw 33 is precluded by an integral circumferential flange 35 which is seated between suitable packing glands. The screw 32 may be conveniently turned, to adjust the tension of the spring 26, by meansof a hand wheel 26 suitably secured to its upper end.

The plug 34 is formed with a peripheral flange 21, to which a plate I! is suitably secured. A housing 32, secured tothis plate by screws 39'- or the like, contains an indicator wheel 40 which is journaled on a hub 4| projecting above the surface oi the plate. Means are provided for 5 turning the indicator wheel 40 one step for each revolution of the hand wheel 38. wheel is provided with a face 42 which may be seen through a window 43 in the housing and which is calibrated to indicate the pressure for which the screw 33, follower 3| and spring 26 are set.

In order to effect the step by step movement of the indicator wheel 40, a rotor 44 is secured to the shank of the screw 33 by a set screw 45 or other suitable means. A plunger 48 is slidably mounted in the rotor and is pressed outwardly by a spring 41, being guided by a pin 48 which projects into a slot 49 in the rotor. The indicator wheel is held against accidental displacement by a snap spring 50 which is mounted in a. recess in the housing 39 and bears against the periphery of the wheel.

A track 52 is formed on the inside of the housing 39 and the plunger 46 is formed with a nose 53 which is adapted to ride on this track as the indicator wheel is rotated. The indicator wheel is provided with a circular row of upstanding pins 54 and with notches in the periphery thereof, which notches are indicated in dotted lines in Figure 3. The track 52 is formed adjacent the window 43 with a curved recess 55 which allows the plunger to be projected by the spring 41 into engagement with one of the pins 54 as it reaches the position shown in Figure 5, moving in the direction of the arrow. As the indicator wheel and plunger reach the position shown in Figure 6, the spring 50 engages one of the notches in the periphery Of the wheel and the position of the latter is stabilized with the pressure reading for which the valve is set visible through the window 43. As the screw 33 is rotated again to increase the pressure, the plunger leaves the recess 55, with the wheel 40 and the pins 54 in the position shown in Figure 7, until the wheel approaches again the completion of a revolution, as shown in Figure 5.

For operation, the inlet II is placed in communication with a fluid supply under pressure and the outlet I2 is connected to the delivery nozzle. The valves 24 and I4 are held closed until the pressure in the chamber l1 and consequently in the chamber 20 reaches the point for which the pilot valve is set to open, as indicated by the The indicator figures visible through the window 43. The opening of the valve 24 relieves the pressure in the chamber 20 faster than it can be built up through the duct 2|, so that the downward pressure on the valve I4 is overbalanced by the upward pressure in the chamber H. The valve then opens against the resistance of the spring l5 to a point which is determined by the length of the inner spring 21. The valve [4 is then held in a stable position without chattering, as long as the fluid supply chamber is maintained at a pressure sufiicient to provide the desired pressure at the nozzle.

If it is desired to set the valve for a higher or lower pressure, all that is necessary to do is to rotate the hand wheel 36 and screw 33 to the right or left, as the case may be, until the desired setting can be read through the window 43.

While for the purpose of illustration, I have shown and described in detail one embodiment of the invention, it is to be understood that it also embraces all such modifications as may be made within the scope of the appended claim.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

The combination with a fluid pressure chamber having an outlet with a seat through which fluid is delivered, of a main relief valve cooperating with said seat and shaped to present unequal opposed pressure areas, the lesser pressure area being in said chamber and tending to open the valve, the larger pressure area tending to close the valve, a second chamber containing the larger pressure area and in constant communication with the first chamber, a third chamber at the end of said valve remote from its seat, a passage through said valve connecting said third chamber to the outlet, a pilot valve, a

chamber within which the pilot valve is normally seated, the pilot valve seat being in constant communication with said second chamber, whereby a predetermined pressure in the latter unseats the valve, a passage from the pilot valve chamber to said third chamber and adapted to be uncovered by the pilot valve only after it has been raised a predetermined distance from its seat.

ARTHUR L. PARKER. 

